knob and tube - Contractor Talk - Professional Construction and Remodeling Forum

tdog2 · 07-21-2005, 10:19 PM

Can someone leave considerable amounts of knob and tube throughout a 75 year-old house, put new outlet covers on, and still say that all rooms have been completely renovated/rehabbed? Or would redoing that electrical be a required element to any reasonable interpretation of "completely renovated/rehabbed"?

thanks for any opinions

mdshunk · 07-22-2005, 09:23 PM

In my opinion, no. That would not qualify as being "completely" anything.

Be advised also that if any of this K&T was insulated in (ie.- walls had batts added or attic insulated over K&T), this is a great big code violation and a bonafide fire hazard. The insulation on K&T does not have sufficient temperature rating to take much heat, and MUST be run in free air in order to properly dissapate the heat built in the conductor. Insuating K&T is expressly not permitted by any code. If this happens to be your case, let me know and I can look up the code citations. Leaving existing K&T installed is not as much of a hazard as insulating it is, in my opinion.

Many of these so-called "rehabs" where K&T is left, the "Handy Hack" or "Joe Six-pack" will also install 3 prong receptacles to give the appearance of grounded receptacles. In fact, any receptacle installed on a K&T system is served with only two wires and not a ground, and is not grounded. There are ways to compliantly install 3 prong receptacles on K&T systems. Let me know also if you need this information. You can still buy brand new 2 prong receptacles if you must put new devices on K&T systems. This is what I generally recommend if you can't afford a bonafide rewire.

reveivl · 07-23-2005, 12:27 AM

"There are ways to compliantly install 3 prong receptacles on K&T systems. Let me know also if you need this information.

If you've got the time to talk more about that, md, I, for one, would be interested. I run into K&T quite a bit. Good info on the insulation issue. Rich.

mdshunk · 07-23-2005, 12:18 PM

There are at least two ways to install 3 prong receptacles on K&T systems:

1) Install a GFCI receptacle at the first receptacle in the string and install 3 prong regular receptacles after that. The GFCI receptacles come with stickers that say "GFCI protected" and more stickers that say "no equipment ground". You are required to put both of these stickers on the 3 prong receptacles that you install after the GFCI, since they are GFCI protectected in the event of a ground fault, but they have no equipment ground.

For practical reasons, this doesn't always work out. K&T is often run around the basement or attic and then a drop is dropped to each receptacle. They often aren't "daisy chained" like we do in these days. With this wiring scheme, there is no real "first receptacle" in the chain that you can protect. Each and every receptacle often would need replaced with a GFCI. You can sometimes find the beginning of that K&T circuit at the panel and install a GFCI receptacle there, to GFCI protect the whole run, and that would permit you to install 3 prong receptacles if they were labeled as described.

2) Install a seperate ground wire. You are permitted to run a seperate green insulated ground wire from the panel's ground buss to each new 3 prong receptacle. This has problems too, since the work involved running this seperate ground wire is often the same amount of work that you'd need to do to rewire that receptacle location anyhow with modern romex.

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On to my editorial...
When you run into K&T, and it is not in the budget to rewire the house, this is what I'd recommend:
1) replace the existing receptacles in most of the house with new 2 prong receptacles. This will not only refresh the look of the devices, but they will hold the prongs of cords in better. The old ones are surely worn out, and no longer hold cords in tightly. Think about it, almost all of the items you plug in the living rooms and bedrooms have two prong cords anyhow.
2) Rewire the bathroom or at least install 3 prong GFCI's in the bathroom
3) Rewire the kitchen at all costs. Pull a couple new 20 amp circuits to the kitchen counter and perhaps two more to the refrigerator location and the microwave location. If you can't rewire the whole dwelling, at least upgrade the kitchen. Electricity usage in the home has changed the most in the kitchen since the time homes were originally wired.

reveivl · 07-23-2005, 11:51 PM

Thanks for the info, clear and concise, Rich.

**ProWallGuy** · 07-23-2005, 11:58 PM

Quote:

Originally Posted by reveivl

Thanks for the info, clear and concise, Rich.

Wørd.

I don't know the first thing about electricity, except that when I touch it with a razor blade and wet hands, it hurts.

Yet, I understood everything you said.

mdshunk · 07-24-2005, 01:45 AM

Reveivl.... I just realized (err... realised

) that you are in Canada. While the CEC is similar to the NEC, some requirements are more strict and some are more lax. Being in the US, I'm not sure if the advice I gave with respect to K&T systems will be compliant in Canada. Please check with your provincial authorities to be sure that any electrical advice you were given mates up with the CEC and any provincial amendments. As the code cycles tick by, the CEC and the NEC are becoming more in line, but there are still some differences.

reveivl · 07-25-2005, 01:30 AM

md, you impress me: you can spell in Canadian!!!

I'm not an electrician, so I wouldn't be doing the work anyhow, just wanted to know the possibilities you know? I do remodeling and run into this stuff and it's helpful to have the right questions to ask the sub. When it comes to information, too much is always better than not enough. Thanks again, Rich.